1. Field of the Invention
The present invention is directed to a method for manufacturing a laminated ceramic electronic component such as a laminated inductor or laminated common-mode choke coil and, more particularly, to a method for manufacturing a laminated ceramic electronic component in which a lamination step is performed using a transfer technique, and a laminated ceramic electronic component that is manufactured by this manufacturing method.
2. Description of the Related Art
Conventional miniaturized inductor components are monolithic coils that are produced using a monolithic ceramic sintering technique. For example, Japanese Unexamined Patent Application Publication No. 56-155516 discloses an open magnetic circuit type monolithic coil as a monolithic inductor. According to the disclosure of this Japanese Application, a magnetic ceramic paste is printed a plurality of times, thereby producing a bottom external layer. A conductor forming a portion of coil, and a magnetic paste are alternately printed. A coil conductor is produced in this way. In the course of printing the coil conductor, a non-magnetic paste is also printed. After the coil conductor is printed, a magnetic paste is printed a plurality of times to form a top external layer. A laminate structure thus produced is pressed in the direction of thickness, and is then sintered. An open magnetic circuit type monolithic coil is thus produced.
In the above-described method of manufacturing the open magnetic circuit type monolithic coil, the laminate structure is obtained by printing the magnetic paste, the non-magnetic paste, and an electrically conductive paste for lamination. In such a lamination-by-printing method, a layer is printed on an already printed layer. The height of a portion where a conductor is printed to form the coil conductor is different from the height of the remaining portion, and the flatness of the printed underlayer is not sufficient. For this reason, the magnetic paste, the non-magnetic paste, or the conductive paste tends to run when they are printed, and a desired monolithic coil cannot be produced with high accuracy.
In the lamination-by-printing method, the magnetic paste, the non-magnetic paste, and the electrically conductive paste used therein in the respective steps require sufficient contact and closeness with the underlayer thereof, and the number of usable types of paste is limited.
In the lamination-by-printing method, an already printed paste needs to be dried to some degree prior to the printing of the next paste. The printing process thus requires much time, and involves complex steps, thereby making it very difficult to reduce the costs of the monolithic coil.
In order to overcome the problems described above, preferred embodiments of the present invention provide a reliable, low-cost and simple-structured, laminated ceramic electronic component, and method of manufacturing the same, which allows a desired conductor and a sintered ceramic internal structure to be produced with high accuracy.
According to a preferred embodiment of the present invention, a method for manufacturing a laminated ceramic electronic component includes the steps of preparing a first transfer member which includes a conductor-attached composite green sheet and a first carrier film supporting the composite green sheet, the composite ceramic green sheet, including a first ceramic region and a second ceramic region made of a ceramic that is different from a ceramic of the first ceramic region, having a conductor on one surface thereof, preparing a second transfer member which includes a ceramic green sheet and a second carrier film supporting the ceramic green sheet, a first transfer step of transferring the ceramic green sheet of at least one second transfer member on a lamination stage, a second transfer step of transferring the conductor-attached composite green sheet of at least one first transfer member to at least one ceramic green sheet already laminated, a third transfer step of transferring the ceramic green sheet of at least one second transfer member to the conductor-attached composite green sheet already laminated, and sintering a laminated body obtained from the first transfer step through the third transfer step.
In another preferred embodiment of the present invention, a method for manufacturing a laminated ceramic electronic component further includes the step of preparing a plurality of first transfer members, and forming a via hole electrode in the composite ceramic green sheet of the conductor-attached composite green sheet of at least one first transfer member so that the conductors are connected among a plurality of conductor-attached composite green sheets subsequent to lamination.
In another preferred embodiment of the present invention, a plurality of conductors are connected through the via hole electrodes to form a coil conductor when the plurality of conductor-attached composite green sheets are laminated.
It is preferable that the first ceramic region is made of a magnetic ceramic, and the second ceramic region is made of a non-magnetic ceramic.
Also, it is preferable that the ceramic sheet of the second transfer member is made of a magnetic ceramic.
The conductor is preferably formed on the top surface of the composite green sheet in the first transfer member.
The conductor is preferably formed on the bottom surface of the composite green sheet in the first transfer member.
The method for manufacturing a laminated ceramic electronic component preferably includes the step of forming the first ceramic region by printing a magnetic ceramic paste and the second ceramic region by printing a non-magnetic ceramic paste.
In a further preferred embodiment of the present invention, the method for manufacturing a laminated ceramic electronic component includes forming the first and second ceramic regions except a region where a via hole electrode is to be formed, and thereafter filling the region with an electrically conductive paste to form the via hole electrode.
In another preferred embodiment of the present invention, the method for manufacturing a laminated ceramic electronic component includes forming a through hole in which a via hole electrode is to be formed after preparing the composite ceramic green sheet, and filling the through hole with an electrically conductive paste to form the via hole electrode.
The ceramic green sheet of the second transfer member is preferably produced by forming a ceramic green sheet on the second carrier film.
In a further preferred embodiment of the present invention, a method for manufacturing a laminated ceramic electronic component further includes preparing a third transfer member which includes a composite ceramic green sheet including the first ceramic region and the second ceramic region, and a third carrier film supporting the composite ceramic green sheet, and transferring the composite ceramic green sheet from at least one third transfer member between the first transfer step and the third transfer step.
In yet another preferred embodiment of the present invention, a laminated ceramic electronic component includes a sintered ceramic body produced according to the manufacturing method according to preferred embodiments of the present invention described above, a plurality of external electrodes arranged on the external surface of the sintered ceramic body, and respectively electrically connected to conductors within the sintered ceramic body.
Another preferred embodiment of the present invention provides a laminated ceramic electronic component including a sintered ceramic body, at least one coil conductor arranged within the sintered ceramic body and including a coil portion and first and second lead-out portions respectively connected to both ends of the coil portion, a plurality of external electrodes arranged on the external surface of the sintered ceramic body and electrically connected to an end of the first lead-out portion or an end of the second lead-out portion, wherein the sintered ceramic body includes a magnetic ceramic and a non-magnetic ceramic, the coil portion of the coil conductor is coated with a non-magnetic ceramic, and the first and second lead-out portions of the coil conductor are coated with a non-magnetic ceramic.
Other features, elements, characteristics and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments with reference to the attached drawings.